Inter Milan full-back Maicon could be out for up to a month after being diagnosed with a muscle strain in his left thigh.
Maicon was injured during Saturday's 2-1 loss to Juventus and the news is a big blow for Inter since the Brazilian has been one of the squad's best performers lately.
Maicon scored a temporary equaliser against Juve and played a full 90 minutes.
With only two wins in its opening nine matches, Inter are hovering only two points above the relegation zone in Serie A.
Inter host Lille in the Champions League on Wednesday.